Pneumatic rubber tires are often manufactured with sidewall or sidewall identifying profile having a contrasting color to the remainder of the tire. Pneumatic rubber tires are typically black in color due to the carbon black particulate reinforcement mixed with the rubber itself. Often such tires are manufactured with a distinctively colored, often white, sidewall on at least one side of the tire and, sometimes with a distinctively colored label, raised letters or numbers or other identification. The white or other contrastingly colored rubber is prepared without carbon black and usually contains a coloring pigment such as, for example, titanium dioxide or other pigment imparting a white or other contrasting color.
Such tires, after they are manufactured, are typically shipped to a designated location where they may then be stored for a period of time. The tires are often stacked one on top of the other or side-by-side against each other, white sidewall to black sidewall, (sometimes referred to as "ricked"), for such shipping and for storage purposes.
It has been observed that the white sidewall of such stacked pneumatic tires can become discolored or stained, primarily due to migration of amine based antidegradants and/or aromatic rubber processing oils contained in the black rubber of the adjacent pneumatic tire. The visual discoloration or staining of the white sidewall normally becomes evident after exposure of such white sidewall rubber containing the migrated staining type materials to ultraviolet light such as sunlight. Such contact staining phenomenon is well known to those having skill in such art.
Often, the surfaces of white sidewall portions of tires are coated with a material or composition to inhibit such chemical migration from one tire to the other and thus, retard or prevent the aforesaid visual staining effect. Polyvinylalcohol (PVA), particularly in a plasticized form, is often used for such purpose because it can be relatively easily applied as a water based solution, provides a reasonable barrier to the representative chemical migration and, because of its water solubility, can later be relatively easily removed by washing from the tire surface when desired. The PVA coat is designed as a relatively temporary coating for tire shipping or storage purposes which is later washed off by the user. However, such PVA coating, partly because of its relatively low abrasion resistance, can be scuffed during shipping and storage conditions and, thus, leaving portions of the white sidewall unprotected and subject to the aforesaid staining effect. Such use of polyvinylalcohol is well known to those having skill in such art.
Tires are also sometimes wrapped with a suitable protective wrapping material for such purpose such as, for example, paper (cellulosic materials), vinylchloride/vinylacetate copolymer and polyester films. However, such wrapping materials, unless they contain an adhesive backing, often become loose around the wrapped tire, thus, presenting an unattractive appearance and sometimes can cause a part of the tire surface to become exposed and, thus, subject to the aforesaid contact staining. Wrappings with an adhesive backing can also become difficult to easily remove from the tire. Sometimes such adhesive backed wrapping was in pieces upon removal. On occasion, it has been observed that stacks of such wrapped tires had become relatively unstable, allowing some tires to tend to slip and fall from the stack.
Therefore, it remains to be desired to provide protective coverings for white sidewall tires to inhibit their visual discoloration caused by contact with black sidewall tires particularly under conditions of storage and shipping and, also, for aesthetic and handling purposes.